Road agencies and construction crews often deploy portable roadway warning devices, such as rumble strips, in work zones and other temporary roadway control locations. The Federal Highway Administration, U.S. Department of Transportation, has provided guidance acknowledging that portable rumble strips are effective in improving driver compliance to warning signs in flagging operations, roadway safety check-points, lane closures, routine maintenance operations, paving operations, or other situations where daily installation and removal may be required. Since work zones are temporary, it is desirable to provide portable rumble strips that may be deployed and removed quickly. However, it may also be desirable that the portable rumble strips not move out of position as vehicles pass over them at highway speeds, and are free of adhesives and/or mounting fasteners. It also is desirable that the rumble strips be reusable.
To reduce the risk of being struck by passing vehicles, it also is desirable that road workers be able to remove the warning devices from the road without entering the roadway. For example, if a plurality of warning device members is deployed across a roadway, it is desirable for the members to remain coupled such that the entire assembly may be removed by retrieving the assembly or device from the side of the road. One warning device, described in U.S. Patent Publication No. US2010/0215431A, includes interlocking notches and tabs, which may be difficult to lock together, and may not maintain a robust connection when removing the assembly or device from the side of the road.
To maintain the portable warning device in position when being run over by vehicles, especially when anchoring devices are avoided in temporary sites, it may be necessary to increase the weight per unit of area of the warning device to a higher value than a comparable thickness of rubber. For example, U.S. Pat. No. 7,736,087 discloses the use of laterally spaced bars or plates within a rubber rumble strip. Such a construction, however, does not allow the strip to match the contour of the roadway in a longitudinal or traffic-flow direction.
In addition, when a vehicle rolls over a strip, a harmonic oscillation may be propagated parallel to the rumble strip. Specifically, when the vehicle's front tires pass over the strip, the strip oscillates while the rear tires pass over the strip. Because the strip is not sitting flat on the ground at that moment, the strip may move in the direction of vehicle travel. As such, the strip may creep forward in the direction of vehicle travel over time.